Lansoprazole
Lansoprazole
Generic Name
Lansoprazole
Mechanism
- Selective, irreversible inhibition of the H⁺/K⁺‑ATPase (the “gastric proton pump”) on the luminal surface of parietal cells.
- Blocks the final step in acid production, producing a profound, long‑lasting decrease in gastric pH.
- Inhibits neurogenic, histaminergic, and gastrin‑stimulated acid secretion, but not basal acid outlet; requires active acid secretion for efficacy.
Pharmacokinetics
| Parameter | Lansoprazole |
| Formulations | Oral capsules, orally disintegrating tablets (ODT), oral suspension; IV 4 mg/5 mL (office use). |
| Absorption | Oral: ~90 % oral bioavailability; IV: 100 %. |
| Distribution | Protein‑binding ~35 % (primarily to albumin). |
| Metabolism | Heterocyclic ring: hydroxylation, N‑dealkylation → 5‑hydroxy‑lansoprazole; UGT1A9 & CYP2C19 primarily. |
| Elimination | Urine (~40 %) and feces (~10 %). Clearance ~0.13 L min⁻¹. |
| Half‑life | ~1–1.5 h (terminal elimination); effect lasts ≈24 h due to irreversible pump inhibition. |
| Drug interactions | Inhibits CYP2C19 → ↑ exposures of clopidogrel, fluconazole, and others; induces CYP3A4 → ↓ clarithromycin, cyclosporine. |
Indications
- Gastro‑esophageal reflux disease (GERD) – healing of erosive esophagitis, maintenance therapy.
- Peptic ulcer disease – healing, ulcer prevention (stress‑induced, NSAID‑related).
- Zollinger–Ellison syndrome – control of gastrin‑stimulated hyperacidity.
- H. *pylori* eradication – part of triple or quadruple therapy.
- Maintenance treatment for patients requiring long‑term acid suppression (e.g., chronic GERD, erosive esophagitis).
Contraindications
- Contraindications:
- Hypersensitivity to lansoprazole or any component.
- Warnings:
- Drug interactions: potent CYP2C19 inhibitors (e.g., ketoconazole) can increase oral exposure; consider IV.
- Clopidogrel: Oral PPIs (including lansoprazole) may reduce clopidogrel activation; use with caution or alternatives (e.g., rabeprazole).
- Severe hepatic impairment: dose adjustment may be necessary.
- Long‑term use (>12 mo): risk of bone fracture, hypomagnesemia, vitamin B12 deficiency.
Dosing
| Condition | Typical Adult Dose | Route | Notes |
| GERD (erosive) | 30 mg PO once daily | 1 h before breakfast | For ≤8 weeks; can dose 15 mg if mild. |
| Maintenance | 15 mg PO once daily | – | For patients who responded to 30 mg. |
| Peptic ulcer (stress‑induced, NSAID) | 30 mg PO once daily | – | Duration 4–8 weeks. |
| Zollinger–Ellison | 60 mg PO twice daily | – | Until symptom control. |
| H. *pylori* eradication | 30 mg PO BID | – | With amoxicillin, clarithromycin, +/– bismuth. |
| IV | 4 mg/5 mL (40 mg 10 mL) | For patients unable to swallow PO | Equivalent to 30 mg PO. |
• Administer ≤30 min before meals for oral dosing.
• ODT: place in mouth; should not be chewed.
• For ketutul: measure serum levels if therapeutic failure (rare).
Adverse Effects
| General | Frequency | Management |
| Headache, dizziness | <5 % | Symptomatic; no dose adjustment usually. |
| Nausea, diarrhea, abdominal pain | 2–5 % | Dietary modification; vanin; consider dose reduction. |
| Flatulence, dyspepsia | <5 % | Symptomatic care. |
| Serious | ||
| Hypomagnesemia (≥3 mo) | <1 % | Monitor serum Mg; supplement if low. |
| Clostridioides difficile colitis | <1 % | Discontinue; treat with oral vancomycin or fidaxomicin. |
| Osteoporotic fracture (long‑term) | <1 % | Calcium/vit B12 supplementation; consider BMD testing. |
| Liver enzyme elevation | 3× ULN. |
Monitoring
- Baseline: CBC, CMP, magnesium, B12 if long‑term therapy.
- Follow‑up (≥3 mo & long‑term):
- Serum magnesium, calcium, vitamin D (if bone risk).
- Liver function tests (if hepatic disease).
- If on clopidogrel: monitor for stent thrombosis events.
- Therapeutic drug monitoring: rarely needed; consider for drug interactions or inadequate response.
Clinical Pearls
- Mini‑dose strategy: For patients with mild GERD, 15 mg once daily after 2–3 weeks of 30 mg may maintain remission and reduce adverse profile.
- IV vs PO: IV lansoprazole is essentially bioequivalent to oral and can be used in critical illness or when oral access is lacking.
- Drug interaction nuance: Lansoprazole is a moderate CYP2C19 inhibitor; it can raise levels of clopidogrel metabolites, reducing antiplatelet potency – consider rabeprazole or esomeprazole if on clopidogrel.
- H. *pylori* regimens: In areas with high clarithromycin resistance, replace clarithromycin with levofloxacin and use a 14‑day duration.
- Long‑term safety: After 12 months of PPI therapy, screen for magnesium deficiency and counsel on calcium‑rich diet, especially in post‑menopausal women.
- PCR‑based testing: For patients with atypical ulcers, consider testing for CYP2C19 genotype to tailor dosing (slow metabolizers may benefit from standard dosing; rapid metabolizers may need 30 mg BID).
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• *This drug card consolidates current data on lansoprazole for rapid reference by medical students and clinicians. Always check local guidelines before prescribing.*